December 19, 2014 

Ms. Penny Lassiter 

Office of Air Quality Planning and Standards (OAQPS) 

Sector Policies and Programs Division (El43-0l) 

Refining and Chemicals Group Leader 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

Re: Supplemental Information - Request for an Alternative Means of Emission Limitation 

("AMEL") for Pressure Assisted Multi-Point Ground Flares ("MPGF') at Baytown Olefins Plant 

and Mont Belvieu Plastics Plant 

Dear Ms. Lassiter: 

Exx.onMobil Chemical Company (ExxonMobil) is respectfully writing to provide supplemental 

infonnation to the Environmental Protection Agency ("EPA") in support of its request for an Alternative 

Means of Emission Limitation ("AMEL"). The AMEL pertains to the flare requirements of New Source 

Perfonnance Standards (NSPS), 40 C.F.R. § 60.18, and National Emission Standards for Hazardous Air 

Pollutants (NESHAP), 40 C.F.R. § 63.11. 

On October 21, 2014, Exx.onMobil requested EPA provide an AMEL for Multi-Point Ground Flares 

(MPGF) at two facilities - Exx.onMobil's Olefins Plant in Baytown, Texas (referred to as "Baytown 

Olefins Plant" or "BOP") and ExxonMobil's Plastics Plant in Mont Belvieu, Texas (referred to as "Mont 

Belvieu Plastics Plant" or "MBPP"). (The request is attached.) We are writing to update you with 

relevant supplemental infonnation since the time of the submission. Specifically, below we provide 

infonnation identifying the chosen suppliers for the MPGFs and establishing that the selected burners 

should be deemed equivalent to those burners for which there is publicly available test data. 

We also recognize that EPA's procedures provide for any proposed AMEL to be subject to public notice 

and comment. As described further below, we respectfully suggest that EPA utilize the opportunity of 

proposing the AMEL and taking comment to allow sufficient flexibility for providing further 

infonnation and data into the record that demonstrates equivalency between various MPGF systems and 

those that have been subject to testing. 

Supplier Selection 

Exx.onMobil's two facilities at BOP and MBPP are being constructed by separate Engineering, 

Procurement and Construction (EPC) contractors. Each EPC has contracted with global leaders in 

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strate a Destruction Efficiency of at least 98% (and 

higher in most cases) for Lower Heating Values above 800 BTU/scf and Lower Flammability Limits 

less than 6.5%. The John Zink supplied burners at MBPP will achieve equivalent results. 

Zeeco Burner Design Comparison 

Although being built by a different vendor, Zeeco's MJ-4 burner is effectively equivalent in 

performance to the John Zink LRGO burner through a design comparison. Equivalency is best assessed 

by comparing the design principles of Burner Type and Burner Geometry for a representative waste gas 

composition that ensures a stable, anchored flame. 

Like the John Zink MPGF burner, Zeeco's burner is pressure assisted. Both burners mix air and waste 

gas using pressure energy inherent in the manufacturing process without steam, air or other assist 

medium. The burner flame is stabilized and anchored by converging jets above a bluff body (a shape 

that creates eddies), resulting in a low pressure zone over a range of velocities. The primary result of this 

type design is stability of the flame over the entire operating envelope. Photos of stable and anchored 

flames with excellent waste gaslair mixing from the Dow 2013 test are shown in Figure 1. 

Figure 1: Photos of stable, anchored and well-mixed flames from the Dow 2013 test 

1 Data obtained from John Zink, Test Report, Flue Gas Emission Testing Support of A TCEQ Alternate Means of Control 

(AMOC) Application From A Pressure Assisted Process Flare And A Steam Assisted Process Flare, Prepared for John Zink 

Company, UC. And The Dow Chemical Company Texas Operation, TRC Project No. 199009, November 2013 and John 

Zink, Test Protocol for The Determination of Destntction Efficiency of Pressure-Assisted and Steam Assisted Flare Burners, 

July 30, 2013. 

2 Data obtained from Clean Air Engineering, Performance Test of Steam·Assisted and Pressure Assisted Ground Flare 

Burners with Passive FT/R • Garyville, March 21, 2013. 

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flammability limit envelope and a higher flame speed than propylene. Therefore, testing with propylene 

results in conservatively high heating value requirements for stable combustion. 

John Zink and Zeeco both utilize the design feature of a pressure assisted burner stabilized by 

converging jets above a bluff body (e.g., Burner Type). Both companies use spider arm burners with 

holes drilled and patterned to achieve smokeless operation over the range of waste gas compositions and 

across the MPGF array (e.g., Burner Geometry). In summary, the John Zink test data can be 

appropriately used to demonstrate equivalency for the Zeeco burners since both suppliers employ the 

same fundamental design principles. 

Additional Data 

ExxonMobil intends to engage in further testing of the burners that will be used at both MBPP and BOP 

in 2015. These tests are intended to confirm the stability of the burners and further demonstrate 

equivalency. ExxonMobillooks forward to sharing the results of the tests with EPA. 

AMEL Flexibility 

As EPA considers a proposed AMEL for MPGFs, ExxonMobil urges the Agency to craft the AMEL 

with sufficient flexibility to establish burner equivalency, given that no two facilities will be precisely 

identical even when they realize equivalent performance results. To this end, we believe that any 

proposed AMEL should be available to sites that demonstrate to EPA's satisfaction that equivalency to 

the flare requirements of New Source Performance Standards (NSPS), 40 C.F.R. § 60.18, and National 

Emission Standards for Hazardous Air Pollutants (NESHAP), 40 C.F.R. § 63.11 is achieved. 

In particular, we believe at least three considerations for AMEL flexibility are appropriate as noted 

below. 

• The AMEL should be available to sites where evidence of equivalency is provided. This 

evidence should allow consideration of both Burner Type and Burner Geometry. 

• Site-specific burner stability testing should be an allowable option of demonstrating that proper 

design and operability are achievable. 

• A range of options for monitoring and recordkeeping of Lower Flammability Limit and Lower 

Heating Value should be considered and proposed. We believe that utilizing operable standards 

until future rulemakings are complete is most appropriate. Specifically, test data supports that 

high Destruction Efficiency for pressure assisted MPGFs is achieved whenever the burners are 

lit. Proven methods such as camera monitoring and operator visual confirmation are already 

available to confirm lit burners. Subject to Agency review and approval, other ground flare lit 

flame assurances provided prior to startup should be allowed. 

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Benjamin M. Hurst 

Environmental Section Supervisor 

cc: Ms. Brenda Shine 

Office of Air Quality Planning and Standards (OAQPS) 

Sector Policies and Programs Division (E143-01) 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

Mr. Andrew Bouchard 

Office of Air Quality Planning and Standards (OAQPS) 

Sector Policies and Programs Division (E 143-01) 

U.S. Environmental Protection Agency 

Research Triangle Park, NC 27711 

Mr. John Blevins 

Director, Compliance and Enforcement Division 

US EPA, Region 6 

1445 Ross Ave. 

Suite 1200 

Mail Code 6 EN 

Dallas, TX 75202-2733 

Mr. Steve Thompson 

Associate Director, Airffoxics Inspection and Coordination Branch 

US EPA, Region 6 

1445 Ross Ave. 

Suite 1200 

Mail Code 6 EN-A 

Dallas, TX 75202-2733 

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